It is known that a water-insoluble polymer having quaternary nitrogen atoms in its molecule (hereinafter referred to as a quaternary nitrogen-containing polymer) adsorbs microorganisms to exhibit antimicrobial activity. For example, JP-A 58-154502 and JP-A 64-26610 disclose the use of such a quaternary nitrogen-containing polymer as an agent for preventing and removing microorganisms and a bactericide of drinking water, cooling water and the like
However, the application of the quaternary nitrogen-containing polymer to oral compositions has not yet been proposed in the field of oral hygiene.
When the quaternary nitrogen-containing polymer is used in oral compositions, since this kind of polymer is cationic, there is a problem that the polymer reacts with normally formulating anionic components such as foaming agents, binders or the like, and thereby significantly decreases in its antimicrobial activity. Therefore, in order to use the quaternary nitrogen-containing polymer in oral compositions, it is necessary to take measures to stabilize it.